This section is intended to provide a background or context to the invention disclosed below. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise explicitly indicated herein, what is described in this section is not prior art to the description in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:                3GPP third generation partnership project        API application programming interface        CDN content delivery network        CEM customer equipment management        CQI channel quality indicator        CSP communications service provider        DL downlink        ECGI E-UTRAN cell global identifier        eNB evolved Node B/base station in an E-UTRAN system        EPC evolved packet core        EUTRAN evolved UT N (LTE)        FDD frequency division duplex        HetNET heterogeneous network        HSS home subscriber server        ID identification        IMSI international mobile subscriber identity        KB kilobyte        LTE long term evolution        LTE-A long term evolution advanced        MME mobility management entity        P2P point-to-point        PLMN public land mobile network        RA routing area        RAN radio access network        RF radio frequency        RNC radio network controller        RRC radio resource control        SNR signal-to-noise ratio        TDD time division duplex        UE user equipment        UL uplink        URI uniform resource identifier        UTRAN universal terrestrial radio access network        
Due to wireless bandwidth constraints within cellular systems, there is an increasing need for techniques which provide lower latency access to requested content. Users may experience unacceptable latency when a wireless or cellular system fails to meet best effort delay requirements or targets. Unacceptable latency may occur at locations where signal strength is poor, such as near cell edges and in the vicinity of terrain obstructions, and where cells are loaded. Many systems provide service to premium users who are considered to be of a higher value or a higher priority than non-premium users. However, latency may prevent these premium users from receiving an acceptable level of service. The foregoing factors prevent many users from having a consistent experience when accessing content over the network.
Content delivery network (CDN) systems are becoming more and more prevalent within wireless communication systems. A CDN is a large distributed network of servers which may be deployed at multiple data centers throughout the Internet. One goal of a CDN is to serve content to end users with high availability and high performance. This content may include, for example, web objects (text, graphics, URLs and scripts), downloadable objects (media files, software, documents), applications (e-commerce, portals), live streaming media, on-demand streaming media, social networks, and other types of data. CDNs offload traffic served directly from a content provider's point of origin infrastructure, typically resulting in greater efficiencies and cost savings for the content provider. CDNs may serve content with dedicated servers, or with point-to-point (P2P) technology based upon peer-operated computers, or both.
Latency can be improved by retrieving content from a cache memory of a local CDN server rather than having to retrieve the content from the Internet on a remotely situated server. At the same time, the rapidly expanding memory capacity provided by present-day user equipment (UE) enhances the potential for UE caching to play a major role in reducing latency and achieving broadband efficiencies. However, conventional CDN systems and UE caching approaches are not sufficiently effective at reducing latency in situations where cells are loaded, where signal strength is poor, where access is attempted at locations near cell edges, and where premium users are to be served.
To perform caching, the CDN or the UE must make a decision as to which content should be retained in a cache memory. For example, the CDN or local server may store information or data objects that were downloaded for a first user such that the information or data objects need not be downloaded again if the information is subsequently requested by a second user. When determining which content should be stored in a cache memory, conventional caching approaches focus on identifying specific content that is most popular across the network, content that is most frequently requested, or content that was most recently requested. One purpose of caching is to enable the CDN or the UE to minimize the volume of traffic which needs to be retrieved from the general Internet down to the communications service provider (CSP) or over the air to the UE. Another purpose of caching is to reduce latency for the largest number of objects retrieved.
As a practical matter, loading on a cellular network is highly non-uniform. To consider an illustrative example, only 20% of the cells in a real-world system may be more than 80% loaded. In general, a small fraction of the cells are loaded whereas a much larger fraction of the cells are underloaded. Caching processes may be improved and latency reduced by differentiating between the popularity of objects retrieved in loaded cells and the popularity of objects retrieved in underloaded cells.
The cost of utilizing radio frequency (RF) resources throughout a cellular network is also highly non-uniform. These RF costs may be expressed in terms of physical resource blocks per kilobyte (KB) of data. The RF costs are much smaller if the user is near the cell tower as opposed to the cell edge. Caching an object to the cell edge saves a disproportionately large amount of eNB resources compared to caching an object near the cell tower. From the standpoint of a user, it is significantly more important to reduce latency at the cell edge versus near the cell tower. Additionally, reducing latency for a object which is being transferred to a user near the tower, is significantly less expensive than producing the same amount of latency reduction for a similar transfer to a user which is instead near the cell edge.
Another factor to consider is the generally non-uniform popularity of objects as a function of geographic location. In other words, it is typical for some objects to be consistently popular in one geographic area whereas other, different objects are consistently popular in other geographic areas. For example, a peer group gathers at a specific location, and everyone in the peer group automatically tends to become interested in the same group of objects. These objects may be items which are located on the Facebook™, LinkedIn™, or MySpace™ pages of the various members of the peer group. Such objects may pertain to sporting events, concerts, parties, and other social occasions. Likewise, a user may live or work at a specific location in an overloaded cell or at a cell edge. In these situations, the user is very likely to request many of the same objects which they have requested in the past, and furthermore the user is very likely to repeat requests for these objects from that specific location. Moreover, as indicated previously, the users themselves are non-uniform with respect to the network in the sense that some users, from a customer equipment management (CEM) perspective, may be of higher priority or value than other users.